Submission #386521

# Submission time Handle Problem Language Result Execution time Memory
386521 2021-04-06T17:50:34 Z SansPapyrus683 Mecho (IOI09_mecho) C++17
84 / 100
685 ms 7756 KB
#include <iostream>
#include <vector>
#include <queue>
#include <climits>

using std::cout;
using std::endl;
using std::vector;
using std::pair;

vector<pair<int, int>> neighbors(const pair<int, int>& at, int row_num, int col_num) {
    vector<pair<int, int>> neighbors;
    if (at.first > 0) {
        neighbors.push_back({at.first - 1, at.second});
    }
    if (at.second > 0) {
        neighbors.push_back({at.first, at.second - 1});
    }
    if (at.first < row_num - 1) {
        neighbors.push_back({at.first + 1, at.second});
    }
    if (at.second < col_num - 1) {
        neighbors.push_back({at.first, at.second + 1});
    }
    return neighbors;
}

class Field {
    private:
        const vector<vector<char>> field;
        const int row_num;
        const int col_num;
        pair<int, int> start;
        vector<vector<int>> bee_dists;
    public:
        Field(const vector<vector<char>>& field)
                : field(field), row_num(field.size()), col_num(field[0].size()),
                  bee_dists(row_num, vector<int>(col_num, INT_MAX)) {
            std::queue<pair<int, int>> frontier;
            for (int r = 0; r < row_num; r++) {
                for (int c = 0; c < col_num; c++) {
                    if (field[r][c] == 'H') {
                        frontier.push({r, c});
                        bee_dists[r][c] = 0;
                    } else if (field[r][c] == 'M') {
                        start = {r, c};
                    }
                }
            }
            while (!frontier.empty()) {
                pair<int, int> c = frontier.front();  // c for curr and to reduce my line length
                frontier.pop();
                int n_cost = bee_dists[c.first][c.second] + 1;
                for (const pair<int, int>& n : neighbors(c, row_num, col_num)) {
                    if (n_cost < bee_dists[n.first][n.second]
                            && field[n.first][n.second] != 'T'
                            && field[n.first][n.second] != 'D') {
                        bee_dists[n.first][n.second] = n_cost;
                        frontier.push(n);
                    }
                }
            }
        }

        bool can_go_home(int honey_time, int speed) {
            std::queue<pair<int, int>> frontier;
            vector<vector<int>> min_moves(row_num, vector<int>(col_num, INT_MAX));
            frontier.push(start);
            min_moves[start.first][start.second] = honey_time * speed;
            while (!frontier.empty()) {
                pair<int, int> curr = frontier.front();
                frontier.pop();
                if (field[curr.first][curr.second] == 'D') {
                    return true;
                }
                int n_cost = min_moves[curr.first][curr.second] + 1;
                for (const pair<int, int>& n : neighbors(curr, row_num, col_num)) {
                    if (field[n.first][n.second] != 'T'
                            && (n_cost / speed) < bee_dists[n.first][n.second]
                            && n_cost < min_moves[n.first][n.second]) {
                        min_moves[n.first][n.second] = n_cost;
                        frontier.push(n);
                    }
                }
            }
            return false;
        }
};

// https://oj.uz/problem/view/IOI09_mecho (sample input ommitted)
int main() {
    int side_len;
    int speed;
    std::cin >> side_len >> speed;
    vector<vector<char>> grid(side_len, vector<char>(side_len));
    for (int r = 0; r < side_len; r++) {
        for (int c = 0; c < side_len; c++) {
            std::cin >> grid[r][c];
        }
    }

    Field field(grid);
    int lo = 0;
    int hi = side_len * side_len;
    int valid = -1;
    while (lo <= hi) {
        int mid = (lo + hi) / 2;
        if (field.can_go_home(mid, speed)) {
            valid = mid;
            lo = mid + 1;
        } else {
            hi = mid - 1;
        }
    }
    cout << valid << endl;
}
# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 384 KB Output is correct
7 Correct 442 ms 7500 KB Output is correct
8 Correct 1 ms 364 KB Output is correct
9 Correct 1 ms 364 KB Output is correct
10 Correct 1 ms 364 KB Output is correct
11 Correct 1 ms 364 KB Output is correct
12 Incorrect 2 ms 364 KB Output isn't correct
13 Incorrect 2 ms 364 KB Output isn't correct
14 Correct 2 ms 364 KB Output is correct
15 Correct 1 ms 364 KB Output is correct
16 Correct 1 ms 364 KB Output is correct
17 Correct 1 ms 384 KB Output is correct
18 Correct 1 ms 364 KB Output is correct
19 Correct 1 ms 364 KB Output is correct
20 Correct 1 ms 364 KB Output is correct
21 Correct 1 ms 364 KB Output is correct
22 Correct 1 ms 364 KB Output is correct
23 Correct 1 ms 364 KB Output is correct
24 Correct 2 ms 364 KB Output is correct
25 Correct 2 ms 364 KB Output is correct
26 Correct 2 ms 364 KB Output is correct
27 Correct 2 ms 384 KB Output is correct
28 Correct 2 ms 364 KB Output is correct
29 Correct 2 ms 364 KB Output is correct
30 Correct 2 ms 384 KB Output is correct
31 Correct 2 ms 364 KB Output is correct
32 Correct 2 ms 364 KB Output is correct
33 Correct 22 ms 1612 KB Output is correct
34 Correct 20 ms 1724 KB Output is correct
35 Correct 96 ms 1796 KB Output is correct
36 Correct 24 ms 1996 KB Output is correct
37 Correct 29 ms 2156 KB Output is correct
38 Correct 146 ms 2476 KB Output is correct
39 Correct 31 ms 2412 KB Output is correct
40 Correct 32 ms 2612 KB Output is correct
41 Correct 171 ms 2728 KB Output is correct
42 Correct 41 ms 2940 KB Output is correct
43 Correct 42 ms 3200 KB Output is correct
44 Correct 215 ms 3164 KB Output is correct
45 Correct 47 ms 3532 KB Output is correct
46 Correct 50 ms 3740 KB Output is correct
47 Correct 243 ms 3724 KB Output is correct
48 Correct 52 ms 3996 KB Output is correct
49 Correct 65 ms 4372 KB Output is correct
50 Correct 305 ms 4324 KB Output is correct
51 Correct 64 ms 4664 KB Output is correct
52 Correct 70 ms 5072 KB Output is correct
53 Correct 376 ms 5240 KB Output is correct
54 Correct 74 ms 5332 KB Output is correct
55 Correct 77 ms 5820 KB Output is correct
56 Correct 444 ms 6004 KB Output is correct
57 Correct 84 ms 6044 KB Output is correct
58 Correct 91 ms 6808 KB Output is correct
59 Correct 535 ms 6628 KB Output is correct
60 Correct 97 ms 6912 KB Output is correct
61 Correct 101 ms 7524 KB Output is correct
62 Correct 592 ms 7592 KB Output is correct
63 Correct 358 ms 7472 KB Output is correct
64 Correct 685 ms 7572 KB Output is correct
65 Correct 517 ms 7620 KB Output is correct
66 Correct 414 ms 7444 KB Output is correct
67 Correct 390 ms 7444 KB Output is correct
68 Correct 181 ms 7596 KB Output is correct
69 Correct 178 ms 7508 KB Output is correct
70 Correct 142 ms 7488 KB Output is correct
71 Correct 164 ms 7700 KB Output is correct
72 Incorrect 129 ms 7532 KB Output isn't correct
73 Incorrect 202 ms 7568 KB Output isn't correct
74 Correct 279 ms 7756 KB Output is correct
75 Correct 340 ms 7456 KB Output is correct
76 Correct 302 ms 7568 KB Output is correct
77 Correct 318 ms 7480 KB Output is correct
78 Correct 366 ms 7448 KB Output is correct
79 Correct 267 ms 7488 KB Output is correct
80 Correct 293 ms 7480 KB Output is correct
81 Correct 327 ms 7480 KB Output is correct
82 Correct 305 ms 7484 KB Output is correct
83 Correct 392 ms 7444 KB Output is correct
84 Correct 360 ms 7468 KB Output is correct
85 Correct 378 ms 7476 KB Output is correct
86 Correct 377 ms 7468 KB Output is correct
87 Correct 378 ms 7464 KB Output is correct
88 Correct 392 ms 7600 KB Output is correct
89 Correct 413 ms 7468 KB Output is correct
90 Correct 423 ms 7456 KB Output is correct
91 Correct 409 ms 7584 KB Output is correct
92 Correct 444 ms 7496 KB Output is correct